A decline in the number of new breast cancers among postmenopausal women coincides with a decline in the use of hormone replacement therapy (HRT), a study published in the Journal of the National Cancer Institute says. Canadian researchers looked at 1,200 Canadian women between the ages of 50 to 69 and found that the number of new breast cancers fell nearly 10 percent between 2002 — the same time a large U.S. clinical trial linked breast cancer and heart and stroke risk to HRT — and 2004.
The study researchers found, however, that the decline in breast cancer incidence was transient and that the rate started to increase again a few years later, suggesting HRT might not necessarily cause breast cancer but might be the impetus for existing cancers to grow more quickly. Lead study author and Canadian Cancer Society epidemiologist Dr. Prithwish De states, “It’s not necessarily a one-to-one relationship as we might assume.”
“The time frame between the discontinued use of HRT and the decline in breast cancer seems to be too short and therefore, the study results don’t seem as credible,” notes ACSH's Dr. Elizabeth Whelan.
“This study’s conclusions are confusing and reminiscent of the equally complex data in the Women’s Health Initiative study from 2002 that claimed HRT causes breast cancer,” says ACSH's Dr. Gilbert Ross. “HRT is a controversial topic, but at least the Society of Obstetricians and Gynecologists of Canada still promotes combined limited-duration HRT therapy as the best treatment of moderate to severe menopausal symptoms.”
